Goal: stop the raiders before they reach the castle gate. Each raider that gets in costs lives.

Build: tap a glowing stone pad and pick a tower.

Archer – fast shots at one target.
Cannon – slow, heavy blast that hits groups.
Frost – chills everyone nearby so they walk slowly.

Upgrade: tap a tower to upgrade it (up to level 3) or sell it.

Hero: tap the ground to move your knight. He fights raiders near him and blocks their way.

Waves: press Start Wave. Calling the next wave early gives bonus gold.

Keys: 1/2/3 build, U upgrade, S sell, Space wave, WASD hero, P pause, M mute, F speed.